1. Field of the Invention
The present invention is generally related to an idler pulley and, more specifically, to an idler pulley that can be manually relocated to a variety of positions to allow the idler pulley to be moved at an optimal position relative to an associated belt or chain.
2. Description of the Prior Art
In many applications where a drive belt is associated with a plurality of pulleys, an idler pulley is used to control the tension of the belt.
U.S. Pat. No. 5,489,243, which issued to Watanabe on Feb. 6, 1996, describes a timing belt tensioner for an engine. A drive arrangement for the cam shaft of an internal combustion engine employed in an outboard motor that includes a pivoted idler pulley that is disposed within the outer periphery of the flywheel, but which has a portion extending beyond the flywheel for adjustment without removing the flywheel is described.
U.S. Pat. No. 5,425,336, which issued to Nakayama on Jun. 20, 1995, describes an outboard motor. Two embodiments of a flexible transmitter tensioning device are described. They afford a screw threaded operation for moving an idler pulley to vary the adjustments. The construction lends itself to incorporation in an outboard motor.
U.S. Pat. No. 5,112,282, which issued to Minato et al on May 12, 1992, describes a driving system for auxiliaries of an engine and a method for adjusting tension of the belt for driving auxiliaries. Plural auxiliaries are independently driven by a belt to suppress an increase in the number of parts and simplify the structure. A cam shaft has first and second driving pulleys disposed in parallel to each other. A first auxiliary having a smaller load against the engine is movably mounted to the engine and has a first following pulley mounted to its operating shaft which is coaxially and rotatably mounted with an idle pulley. On the other hand, a second auxiliary having a larger load against the engine is fixed to the engine. To the engine is movably mounted a tension pulley. A first belt for driving the first auxiliary is wound around the first following pulley, the first driving pulley and a tension pulley, while a second belt for driving the second auxiliary is wound around the second driving pulley and the idle pulley. The tension of the first belt is adjusted by transferring the tension pulley, while the tension of the second belt is adjusted by transferring the first auxiliary.
U.S. Pat. No. 4,768,997, which issued to Page et al on Sep. 6, 1988, describes a belt drive system for dual input transmissions and transaxles. A two belt drive system is disclosed for lawn and garden tractors and other vehicles especially of the type including a variable speed transmission/transaxle having a constant speed rotational input, a variable speed rotational input and an output speed dependent on the rotational speed of the variable input. A first drive belt is mounted for rotation in one direction on an engine drive pulley, a first pulley of one of the transmission/transaxle inputs, and one pulley of a variable diameter pulley assembly. A second drive belt is mounted for rotation in the same direction as the first belt on a second pulley on the other transmission/transaxle input and the other pulley of the variable pulley assembly. Shifting the position of the variable pulley assembly with a hand control changes the belt receiving diameters of the variator pulleys such that the rotational speed of the second drive belt, second pulley, transmission/transaxle output, and resulting ground speed of the tractor are all adjustable with a hand control while the engine drives the first belt at a constant rotational speed.
U.S. Pat. No. 4,713,044, which issued to Nakamura et al on Dec. 15, 1987, describes a belt tensioner unit for an internal combustion engine or the like. The arm on which the idler pulley is supported as well as the tensioner which biases the arm to tension a timing belt or the like are both mounted on a common base plate. The plate is pivotally supported on the engine block and selectively securable in a desired position. A stopper mechanism which can be used to temporarily disable the biasing and damping functions of the tensioner enables automatic tension setting.
U.S. Pat. No. 4,270,906, which issued to Kraft et al on Jun. 2, 1981, describes a belt tensioner construction. A belt tensioner for an endless drive belt for vehicle accessories has a shaft which is mounted in a fixed position adjacent the belt. A lever is pivotally mounted on the shaft and has an idler pulley rotatably mounted on an extended end of the lever. The pulley is movable into tensioning engagement with the belt by rotation of the lever. A first cam plate is slidably mounted on the shaft and is engaged with a second cam plate which is attached to the lever for rotation with the lever. The cam plates each have a plurality of a series of camming surfaces which are mutually engageable with the opposite cam plate surfaces. A plurality of spring discs are telescopically mounted on the shaft and bias the first camming block into engagement with the second block applying a rotational force on the lever to move the pulley into tensioning relation with the drive belt. A hub is adjustably mounted on the shaft and is in abutting engagement with the springs to adjust the amount of camming force exerted on the lever, and correspondingly, on the belt by the idler pulley.
U.S. Pat. No. 4,193,315, which issued to Noe on Mar. 18, 1980, describes a belt drive system utilizing an adjustable idler mechanism. The adjustable idler mechanism is intended for use with a drive belt system in a laundry appliance. The idle mechanism includes first and second bell cranks pivoted about a common point and interconnected by a threaded member for adjustment with respect to each other to place tension on the drive belt. A solenoid is provided to disengage the idler mechanism from the drive belt from predetermined portions of a cycle of operations.
U.S. Pat. No. 3,763,715, which issued to Pollard et al on Oct. 9, 1973, describes an auxiliary tightener for fan belts on automobile engines. The auxiliary tightener for fan belts on automobile engines consists of an idler pulley on a movable mounting bracket located in the normal path of a fan belt on an automobile engine so as to relocate the path of the fan belt and thus enable the regular adjustable tensioning device to be effective in maintaining working tension on the belt. In some automobile engines having overhead cam shafts milling the head to increase the compression ratio in the engine results in lowering the cam shaft to a position where the usual fan belt drives the cam shaft, is incapable of maintaining proper frictional engagement with the drive pulleys of the engine. On such engines the use of the auxiliary tightener enables the cam shaft to be properly driven and the timing of the engine to be set as desired.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
It would be significantly beneficial if an idler pulley could be provided which allows it to be rigidly attached to a stationary object in any one of a preselected plurality of alternative positions relative to the stationary object. It would also be significantly beneficial if such a variably locatable idler pulley could be made with fewer required parts than idler pulleys which are known in the prior art.
An idler pulley made in accordance with the preferred embodiment of the present invention comprises a hub portion and a rotatable portion which is rotatable relative to the hub portion. The rotatable portion is rotatable about a central axis. A first attachment location, which can be a hole formed through the hub portion, is provided at a location which is displaced from the central axis of the rotatable portion. The first attachment location is shaped to be attachable to a first anchor location on a stationary object, such as an internal combustion engine. A second attachment location, which can be a second hole formed through the hub portion, is shaped to be attachable to a second anchor location on the stationary object. The hub portion is rigidly attachable to the stationary object when the first attachment location is attached to the first anchor location and the second attachment location is attached to the second anchor location.
In a preferred embodiment of the present invention, the central axis extends through the hub portion. A plurality of roller bearings is disposed between the hub portion and the rotatable portion. The first and second attachment locations are holes formed through the hub portion to allow threaded fasteners to pass through the holes and be attached to associated anchor locations on the stationary object. The rotatable portion of the idler pulley can be a crowned pulley.
In a preferred embodiment of the present invention, third and fourth attachment locations are formed on the hub portion and are shaped to be attachable, alternatively, to the second anchor location on the stationary object. The hub portion can be rigidly attached to the stationary object when the first attachment location is attached to the first anchor location and either of the second and third attachment locations are attached to the second anchor location. In a preferred embodiment of the present invention, the second, third, and fourth attachment locations are located on an arc of a first circle having its center at the first attachment location.
Fifth and sixth attachment locations can also be formed on the hub portion and shaped to be alternatively attachable to the second anchor location on the stationary object. The hub portion is rigidly attachable to the stationary object when the first attachment location is attached to the first anchor location and either the fifth or sixth attachment locations is attached to the second anchor location. The fifth and sixth attachment locations are located on an arc of a second circle having its center at the first attachment location. All of the attachment locations described above are holes formed through the hub portion in a preferred embodiment of the present invention.